1. Field of the Invention
Embodiments of the present invention generally relate to systems and methods for disinfecting water, and in particular, systems and methods for disinfecting potable water supplies on board passenger transportation vehicles and equipment, such as aircraft, trains, boats, ships, and the like. One embodiment particularly relates to systems and methods for disinfecting drinkable water at the point of use. Further embodiments relate to safety features that may be provided on systems for disinfecting water.
2. Description of Related Art
The issue of water quality, and in particular, of potable water quality, on passenger transportation vehicles and equipment, such as aircraft, trains, boats and ships, and the like is becoming more of a concern to regulatory authorities. This is particularly true in the United States with respect to the potable water supplies contained aboard commercial aircraft. Regulatory standards have been enacted that require water on board passenger vehicles to be disinfected according to certain standards. Passenger airlines must thus implement appropriate aircraft water disinfection protocols.
U.S. Pat. No. 4,871,452 to Kohler, et al., entitled “On-Board Water Supply,” discloses equipment for purifying waste water from galleys, sinks, and toilets of aircraft. Waste water from these areas discharges to a tank, after which it passes through a mechanical filter, a bed of active carbon, ozone and osmotic stages, and a disinfection stage involving addition of chlorine and irradiation with ultraviolet (“UV”) light. Thereafter, the water is made available to aircraft passengers for certain uses.
U.S. Pat. No. 6,143,185 to Tracy, et al. entitled “Treatment System for Aircraft Toilet Waster Water” discloses alternate systems for decontaminating waste water from aircraft toilets, sinks, and galleys. They too include a mechanical particulate filter, activated carbon, and a source of UV light. Alternatively, according to the Tracy patent, the waste water may be exposed to microwaves or treated with chlorine or iodine. A sensor may be used to measure “the level of clarity of the treated water as an indication of its purity” and restrict opening of a control valve until acceptable clarity levels are obtained.
However, these systems and methods are primarily directed at purifying wastewater removed from the aircraft. Airlines and other passenger transport vehicle companies must also ensure that the potable water (i.e., drinkable water) aboard the aircraft is fit for human consumption by employing appropriate disinfection protocols. But disinfection upon upload and periodic disinfection sampling does not always adequately address the issue of contamination introduced in uploaded water, which is of particular concern for aircraft flying to and from, and being serviced in, non-industrialized areas. In addition, air must be introduced into the water storage and dispensing system on the aircraft in order to maintain pressurization, as well as to drain the system during routine servicing. This air can introduce pathogens that can multiply and cause unsanitary conditions and unacceptable water quality in the intervals between samplings or disinfection procedures. In effect, because the water storage and dispensing system is routinely exposed to the outside environment, potable water quality cannot always be ensured without some form of additional treatment.
Continuous treatment of potable water supplies presents its own set of potential problems to be solved, including continuous or semi-continuous dosing of the water with the requisite dosing equipment (metering and monitoring equipment, dosing agent storage equipment, and/or equipment for in-situ generation of the dosing agent). Accordingly, attempts have been made to purify water while on-board an aircraft or other passenger vehicles directly at the point of use. For example, U.S. Publication No. 2010/0133155 to Nolan entitled “Water Distribution System With Dual Use Water Treatment Unit” discloses systems for treating water by irradiation with UV light, along with an activated carbon or sediment filter. The water is either treated on upload or at the point of use. Other attempts to treat water have occurred at the point at which water leaves the on-board water tank, before it travels to the point of use location.
However, there remains a need in the art for systems and methods for point of use treatment of potable water supplies to purify the dispensed water supplies, and related safety features and improved UV light sources.